Cargando…

Arginine deiminase pathway is far more important than urease for acid resistance and intracellular survival in Laribacter hongkongensis: a possible result of arc gene cassette duplication

BACKGROUND: Laribacter hongkongensis is a Gram-negative, urease-positive bacillus associated with invasive bacteremic infections in liver cirrhosis patients and fish-borne community-acquired gastroenteritis and traveler’s diarrhea. Its mechanisms of adaptation to various environmental niches and hos...

Descripción completa

Detalles Bibliográficos
Autores principales: Xiong, Lifeng, Teng, Jade LL, Watt, Rory M, Kan, Biao, Lau, Susanna KP, Woo, Patrick CY
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2014
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3936950/
https://www.ncbi.nlm.nih.gov/pubmed/24533585
http://dx.doi.org/10.1186/1471-2180-14-42
_version_ 1782305397756919808
author Xiong, Lifeng
Teng, Jade LL
Watt, Rory M
Kan, Biao
Lau, Susanna KP
Woo, Patrick CY
author_facet Xiong, Lifeng
Teng, Jade LL
Watt, Rory M
Kan, Biao
Lau, Susanna KP
Woo, Patrick CY
author_sort Xiong, Lifeng
collection PubMed
description BACKGROUND: Laribacter hongkongensis is a Gram-negative, urease-positive bacillus associated with invasive bacteremic infections in liver cirrhosis patients and fish-borne community-acquired gastroenteritis and traveler’s diarrhea. Its mechanisms of adaptation to various environmental niches and host defense evasion are largely unknown. During the process of analyzing the L. hongkongensis genome, a complete urease cassette and two adjacent arc gene cassettes were found. We hypothesize that the urease cassette and/or the arc gene cassettes are important for L. hongkongensis to survive in acidic environment and macrophages. In this study, we tested this hypothesis by constructing single, double and triple non-polar deletion mutants of the urease and two arc gene cassettes of L. hongkongensis using the conjugation-mediated gene deletion system and examining their effects in acidic environment in vitro, in macrophages and in a mouse model. RESULTS: HLHK9∆ureA, HLHK9∆ureC, HLHK9∆ureD and HLHK9∆ureE all exhibited no urease activity. HLHK9∆arcA1 and HLHK9∆arcA2 both exhibited arginine deiminase (ADI) activities, but HLHK9∆arcA1/arcA2 double deletion mutant exhibited no ADI activity. At pH 2 and 3, survival of HLHK9∆arcA1/arcA2 and HLHK9∆ureA/arcA1/arcA2 were markedly decreased (p < 0.001) but that of HLHK9∆ureA was slightly decreased (p < 0.05), compared to wild type L. hongkongensis HLHK9. Survival of HLHK9∆ureA/arcA1/arcA2 and HLHK9∆arcA1/arcA2 in macrophages were also markedly decreased (p < 0.001 and p < 0.01 respectively) but that of HLHK9∆ureA was slightly decreased (p < 0.05), compared to HLHK9, although expression of arcA1, arcA2 and ureA genes were all upregulated. Using a mouse model, HLHK9∆ureA exhibited similar survival compared to HLHK9 after passing through the murine stomach, but survival of HLHK9∆arcA1/arcA2 and HLHK9∆ureA/arcA1/arcA2 were markedly reduced (p < 0.01). CONCLUSIONS: In contrast to other important gastrointestinal tract pathogens, ADI pathway is far more important than urease for acid resistance and intracellular survival in L. hongkongensis. The gene duplication of the arc gene cassettes could be a result of their functional importance in L. hongkongensis.
format Online
Article
Text
id pubmed-3936950
institution National Center for Biotechnology Information
language English
publishDate 2014
publisher BioMed Central
record_format MEDLINE/PubMed
spelling pubmed-39369502014-02-28 Arginine deiminase pathway is far more important than urease for acid resistance and intracellular survival in Laribacter hongkongensis: a possible result of arc gene cassette duplication Xiong, Lifeng Teng, Jade LL Watt, Rory M Kan, Biao Lau, Susanna KP Woo, Patrick CY BMC Microbiol Research Article BACKGROUND: Laribacter hongkongensis is a Gram-negative, urease-positive bacillus associated with invasive bacteremic infections in liver cirrhosis patients and fish-borne community-acquired gastroenteritis and traveler’s diarrhea. Its mechanisms of adaptation to various environmental niches and host defense evasion are largely unknown. During the process of analyzing the L. hongkongensis genome, a complete urease cassette and two adjacent arc gene cassettes were found. We hypothesize that the urease cassette and/or the arc gene cassettes are important for L. hongkongensis to survive in acidic environment and macrophages. In this study, we tested this hypothesis by constructing single, double and triple non-polar deletion mutants of the urease and two arc gene cassettes of L. hongkongensis using the conjugation-mediated gene deletion system and examining their effects in acidic environment in vitro, in macrophages and in a mouse model. RESULTS: HLHK9∆ureA, HLHK9∆ureC, HLHK9∆ureD and HLHK9∆ureE all exhibited no urease activity. HLHK9∆arcA1 and HLHK9∆arcA2 both exhibited arginine deiminase (ADI) activities, but HLHK9∆arcA1/arcA2 double deletion mutant exhibited no ADI activity. At pH 2 and 3, survival of HLHK9∆arcA1/arcA2 and HLHK9∆ureA/arcA1/arcA2 were markedly decreased (p < 0.001) but that of HLHK9∆ureA was slightly decreased (p < 0.05), compared to wild type L. hongkongensis HLHK9. Survival of HLHK9∆ureA/arcA1/arcA2 and HLHK9∆arcA1/arcA2 in macrophages were also markedly decreased (p < 0.001 and p < 0.01 respectively) but that of HLHK9∆ureA was slightly decreased (p < 0.05), compared to HLHK9, although expression of arcA1, arcA2 and ureA genes were all upregulated. Using a mouse model, HLHK9∆ureA exhibited similar survival compared to HLHK9 after passing through the murine stomach, but survival of HLHK9∆arcA1/arcA2 and HLHK9∆ureA/arcA1/arcA2 were markedly reduced (p < 0.01). CONCLUSIONS: In contrast to other important gastrointestinal tract pathogens, ADI pathway is far more important than urease for acid resistance and intracellular survival in L. hongkongensis. The gene duplication of the arc gene cassettes could be a result of their functional importance in L. hongkongensis. BioMed Central 2014-02-17 /pmc/articles/PMC3936950/ /pubmed/24533585 http://dx.doi.org/10.1186/1471-2180-14-42 Text en Copyright © 2014 Xiong et al.; licensee BioMed Central Ltd. http://creativecommons.org/licenses/by/2.0 This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited.
spellingShingle Research Article
Xiong, Lifeng
Teng, Jade LL
Watt, Rory M
Kan, Biao
Lau, Susanna KP
Woo, Patrick CY
Arginine deiminase pathway is far more important than urease for acid resistance and intracellular survival in Laribacter hongkongensis: a possible result of arc gene cassette duplication
title Arginine deiminase pathway is far more important than urease for acid resistance and intracellular survival in Laribacter hongkongensis: a possible result of arc gene cassette duplication
title_full Arginine deiminase pathway is far more important than urease for acid resistance and intracellular survival in Laribacter hongkongensis: a possible result of arc gene cassette duplication
title_fullStr Arginine deiminase pathway is far more important than urease for acid resistance and intracellular survival in Laribacter hongkongensis: a possible result of arc gene cassette duplication
title_full_unstemmed Arginine deiminase pathway is far more important than urease for acid resistance and intracellular survival in Laribacter hongkongensis: a possible result of arc gene cassette duplication
title_short Arginine deiminase pathway is far more important than urease for acid resistance and intracellular survival in Laribacter hongkongensis: a possible result of arc gene cassette duplication
title_sort arginine deiminase pathway is far more important than urease for acid resistance and intracellular survival in laribacter hongkongensis: a possible result of arc gene cassette duplication
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3936950/
https://www.ncbi.nlm.nih.gov/pubmed/24533585
http://dx.doi.org/10.1186/1471-2180-14-42
work_keys_str_mv AT xionglifeng argininedeiminasepathwayisfarmoreimportantthanureaseforacidresistanceandintracellularsurvivalinlaribacterhongkongensisapossibleresultofarcgenecassetteduplication
AT tengjadell argininedeiminasepathwayisfarmoreimportantthanureaseforacidresistanceandintracellularsurvivalinlaribacterhongkongensisapossibleresultofarcgenecassetteduplication
AT wattrorym argininedeiminasepathwayisfarmoreimportantthanureaseforacidresistanceandintracellularsurvivalinlaribacterhongkongensisapossibleresultofarcgenecassetteduplication
AT kanbiao argininedeiminasepathwayisfarmoreimportantthanureaseforacidresistanceandintracellularsurvivalinlaribacterhongkongensisapossibleresultofarcgenecassetteduplication
AT laususannakp argininedeiminasepathwayisfarmoreimportantthanureaseforacidresistanceandintracellularsurvivalinlaribacterhongkongensisapossibleresultofarcgenecassetteduplication
AT woopatrickcy argininedeiminasepathwayisfarmoreimportantthanureaseforacidresistanceandintracellularsurvivalinlaribacterhongkongensisapossibleresultofarcgenecassetteduplication